ARS researchers in Peoria, Illinois,
have devised a way to convert the oil's fatty acids into entirely new
compounds having antimicrobial, medical, and industrial properties.

One, called 7(S),10(S)-dihydroxy-8(E)-octadecenoic acidor DODstopped
the growth of Candida albicans yeast, a human pathogen, in laboratory
experiments. Another, TOD, curtailed rice blast fungus, raising the
prospect of a biofungicide to control this crop scourge.

Both compounds are now patented and available for licensing and further
testing by private industry. They're also recent examples of the Peoria
researchers' efforts to open new market outlets for vegetable oils,
particularly surplus soybean oil.

The scientists' approach is called bioconversion, a process that uses
certain microorganisms or enzymes to reposition groups of hydroxy fatty
acids on chains of carbon in vegetable oils.

"Using bioconversion, we can produce many value-added products
from these fatty acids," says Ching Hou, a biochemist and lead
scientist at the ARS National Center for Agricultural Utilization Research's
Microbial Genomics and Bioprocessing Research Unit in Peoria. "The
process can create completely new chemical entities."

Key to bioconversion is a favorable environment in which its microbial
workhorsesmainly bacteria and yeastscan feed on and catalyze
fatty acids inside special fermentation tanks called bioreactors. While
not yet as efficient as chemically driven processes, bioconversion offers
other advantages.

"When you produce something by chemical means, there will be undesirable
wastes generated as a result. Bioconversion is a more specific process
and generates fewer byproducts," notes ARS chemist Tsung Kuo, who
is exploring ways to scale up the technology and optimize the microbes'
performance.

One bacterium, a Pseudomonas aeruginosa strain called PR3, is
the driving force behind a bioconversion process to produce DOD from
oleic acid in soybean oil and TOD7,10,12-trihydroxy-8(E)-octadecenoic
acidfrom ricinoleic acid in castor oil.

The bacterial system converts up to 89 percent of oleic acid into DOD
and up to 45 percent of ricinoleic acid into TOD in small fermentation
flasks, reports Kuo. The Peoria bioconversion team also includes chemist
Alan Lanser, support scientist Linda Manthey, and biological technicians
Wanda Brown and Karen Ray.

Biobased compounds have several potential uses. For example, DOD, in
addition to stopping yeast growth, is structurally similar to surfactants,
like those in soap, and has properties applicable for use in plastics
and other industrial products.

TOD is also antimicrobial. When sprayed onto plants, it provided varying
levels of control against rice blast, wheat leaf rust, and three different
blight pathogens. When mixed with water and acetone at 200 parts per
million (ppm), TOD killed 100 percent of fruit flies and at concentrations
of 250 ppm killed 90 percent of two-spotted spider mites.

The Peoria scientists have produced three other novel compounds by
bioconversion. One, called THFA for short, is derived from linoleic
acid in soybean oil and resembles tetrahydrofuranyl compounds, which
are known cancer fighters.By Jan
Suszkiw, Agricultural Research Service Information Staff.

This research is part of Quality and Utilization of Agricultural
Products, an ARS National Program (#306) described on the World Wide
Web at http://www.nps.ars.usda.gov.